Taking "representation of an action " as its central point, this text discusses the aesthetic traits of the plot, character, and thought in the structure of ancient Greek drama, especially on the plot composition from complication to resolution. First, this essay re-examine the reading of Katharsis as a concept of structure in the definition of tragedy by Aristotle, such as the saying of Papanouzous 1953, and that of Else 1957:and this is the main point of the study here. Next, the author indicates the origins of the world of ancient Greek drama according to the survived text, discusses its tradition of myth, event-structure of ancient Greek epics and the original genre of poetry such as dithyramb and satyr-play. The main lines study in this section is to resume the action of Greek drama in the family of Orestes, that of Oedipus, and that of Thuestes etc. Thirdly, this text examine the logic of the developments of ancient Greek drama on three levels of the structure: its generality (to katholon), its probability and necessity ,and its reality that can be compared to the real world in ancient Greece. To conclude, the author proposes four categories for analyzing ancient Greek world of drama; and continually discuses the complementing feature Between "the representation of an action" and "the exciting of emotions" that are of the problem in analyzing the structure of drama.